19 



when it is mutilated. I have known this milky appear- 

 ance of the mutilated mantle of the oyster to lead per- 

 sons to mistake it for the reproductive organ ; a mistake 

 easily made by the inexperienced. 



The preceding account of the physiology of the so- 

 called fattening process will serve to prove how little 

 philosophy there is in the doctrine that oysters may be 

 fattened by putting them for a day or two in water less 

 salt than that from which they were first taken, in order 

 that they may be water-swollen by the action of osmose 

 so as to give them a plump appearance. 



Upon making an examination of some oysters to-day 

 (Dec. 6th,) to learn something in regard to the nature of 

 the so-called fatty material contained in the thickened 

 mantle, I find that it is made up of nucleated cells com- 

 posed of a line corpuscular material. The protoplasmic 

 granules are so fine that they remind one, when exam- 

 ined under a power of 250 diameters, of the corpuscles 

 found in milk, though they are probably quite different 

 in nature. They manifest the dancing motion when 

 highly magnified, which is known as pedesis or the 

 Brownian movement, and appear to be perfectly spheri- 

 cal with considerable variation in size. Upon examining 

 another specimen I found the principal ducts of the 

 testes already defined, and upon microscopic examination 

 an abundance of active, though not perfectly mature, 

 spermatozoa were noticed. The spermaries in this case 

 may no doubt be considered as a part of the fat, but the 

 case is most interesting as showing how very early in the 

 season the generative products commence to develop. 



FOOD OF THE OYSTEK. 



The food of this mollusk, as is well known, consists 

 entirely of microscopic beings and fragments of organic 

 matter, which are carried by currents from the palps and 

 gills, which have been already described, to the large 

 mouth of the animal at the hinge end of the shell. The 

 inside of the gullet and stomach, like some other parts of 



